macro: reserve for custom SBI extensions

Signed-off-by: Zhouqi Jiang <[email protected]>

examples/derive/commons.rs

@@ -1,7 +1,7 @@
 // Mock implementaion module. Actual SBI implementaion should implement
 // those SBI extensions with machine environment specific hardware features.
 
-use rustsbi::{HartMask, EnvInfo};
+use rustsbi::{EnvInfo, HartMask};
 use sbi_spec::binary::SbiRet;
 
 pub struct MyFence;

src/traits.rs

@@ -27,43 +27,23 @@ pub trait EnvInfo {
     fn mimpid(&self) -> usize;
 }
 
-/* macro internal structures and functions */
-
-#[doc(hidden)]
-pub struct _StandardExtensionProbe {
-    pub base: usize,
-    pub fence: usize,
-    pub timer: usize,
-    pub ipi: usize,
-    pub hsm: usize,
-    pub reset: usize,
-    pub pmu: usize,
-    pub console: usize,
-    pub susp: usize,
-    pub cppc: usize,
-    pub nacl: usize,
-    pub sta: usize,
-    // NOTE: don't forget to add to `fn probe_extension` as well
-}
+// Macro internal structures and functions.
+// DO NOT USE code here directly; use derive macro #[derive(RustSBI)] instead.
 
 #[cfg(feature = "machine")]
 #[doc(hidden)]
 #[inline(always)]
-pub fn _rustsbi_base_bare(
+pub fn _rustsbi_base_bare<U: _ExtensionProbe>(
     param: [usize; 6],
     function: usize,
-    probe: _StandardExtensionProbe,
+    probe: U,
 ) -> SbiRet {
     let [param0] = [param[0]];
     let value = match function {
         spec::base::GET_SBI_SPEC_VERSION => (crate::SBI_SPEC_MAJOR << 24) | (crate::SBI_SPEC_MINOR),
         spec::base::GET_SBI_IMPL_ID => crate::IMPL_ID_RUSTSBI,
         spec::base::GET_SBI_IMPL_VERSION => crate::RUSTSBI_VERSION,
-        spec::base::PROBE_EXTENSION => {
-            // only provides probes to standard extensions. If you have customized extensions to be probed,
-            // run it even before this `handle_ecall` function.
-            probe_extension(param0, probe)
-        }
+        spec::base::PROBE_EXTENSION => probe.probe_extension(param0),
         spec::base::GET_MVENDORID => mvendorid::read().map(|r| r.bits()).unwrap_or(0),
         spec::base::GET_MARCHID => marchid::read().map(|r| r.bits()).unwrap_or(0),
         spec::base::GET_MIMPID => mimpid::read().map(|r| r.bits()).unwrap_or(0),
@@ -74,22 +54,18 @@ pub fn _rustsbi_base_bare(
 
 #[doc(hidden)]
 #[inline(always)]
-pub fn _rustsbi_base_env_info<T: EnvInfo>(
+pub fn _rustsbi_base_env_info<T: EnvInfo, U: _ExtensionProbe>(
     param: [usize; 6],
     function: usize,
     machine_info: &T,
-    probe: _StandardExtensionProbe,
+    probe: U,
 ) -> SbiRet {
     let [param0] = [param[0]];
     let value = match function {
         spec::base::GET_SBI_SPEC_VERSION => (crate::SBI_SPEC_MAJOR << 24) | (crate::SBI_SPEC_MINOR),
         spec::base::GET_SBI_IMPL_ID => crate::IMPL_ID_RUSTSBI,
         spec::base::GET_SBI_IMPL_VERSION => crate::RUSTSBI_VERSION,
-        spec::base::PROBE_EXTENSION => {
-            // only provides probes to standard extensions. If you have customized extensions to be probed,
-            // run it even before this `handle_ecall` function.
-            probe_extension(param0, probe)
-        }
+        spec::base::PROBE_EXTENSION => probe.probe_extension(param0),
         spec::base::GET_MVENDORID => machine_info.mvendorid(),
         spec::base::GET_MARCHID => machine_info.marchid(),
         spec::base::GET_MIMPID => machine_info.mimpid(),
@@ -98,22 +74,50 @@ pub fn _rustsbi_base_env_info<T: EnvInfo>(
     SbiRet::success(value)
 }
 
-#[inline(always)]
-fn probe_extension(extension: usize, probe: _StandardExtensionProbe) -> usize {
-    match extension {
-        spec::base::EID_BASE => probe.base,
-        spec::time::EID_TIME => probe.timer,
-        spec::spi::EID_SPI => probe.ipi,
-        spec::rfnc::EID_RFNC => probe.fence,
-        spec::srst::EID_SRST => probe.reset,
-        spec::hsm::EID_HSM => probe.hsm,
-        spec::pmu::EID_PMU => probe.pmu,
-        spec::dbcn::EID_DBCN => probe.console,
-        spec::susp::EID_SUSP => probe.susp,
-        spec::cppc::EID_CPPC => probe.cppc,
-        spec::nacl::EID_NACL => probe.nacl,
-        spec::sta::EID_STA => probe.sta,
-        _ => spec::base::UNAVAILABLE_EXTENSION,
+// Probe not only standard SBI extensions, but also (reserving for) custom extensions.
+// For standard SBI extensions only, the macro would use `_StandardExtensionProbe`;
+// for implementation with custom SBI extension, a custom structure implementing this trait
+// would be used by macro.
+pub trait _ExtensionProbe {
+    // Implementors are encouraged to add #[inline] hints on this function.
+    fn probe_extension(&self, extension: usize) -> usize;
+}
+
+#[doc(hidden)]
+pub struct _StandardExtensionProbe {
+    pub base: usize,
+    pub fence: usize,
+    pub timer: usize,
+    pub ipi: usize,
+    pub hsm: usize,
+    pub reset: usize,
+    pub pmu: usize,
+    pub console: usize,
+    pub susp: usize,
+    pub cppc: usize,
+    pub nacl: usize,
+    pub sta: usize,
+    // NOTE: don't forget to add to `fn probe_extension` in `impl _ExtensionProbe` as well
+}
+
+impl _ExtensionProbe for _StandardExtensionProbe {
+    #[inline(always)]
+    fn probe_extension(&self, extension: usize) -> usize {
+        match extension {
+            spec::base::EID_BASE => self.base,
+            spec::time::EID_TIME => self.timer,
+            spec::spi::EID_SPI => self.ipi,
+            spec::rfnc::EID_RFNC => self.fence,
+            spec::srst::EID_SRST => self.reset,
+            spec::hsm::EID_HSM => self.hsm,
+            spec::pmu::EID_PMU => self.pmu,
+            spec::dbcn::EID_DBCN => self.console,
+            spec::susp::EID_SUSP => self.susp,
+            spec::cppc::EID_CPPC => self.cppc,
+            spec::nacl::EID_NACL => self.nacl,
+            spec::sta::EID_STA => self.sta,
+            _ => spec::base::UNAVAILABLE_EXTENSION,
+        }
     }
 }